Tuesday, February 13th, 2024

Time	Event
12:36a	Enhancement of Temporal Processing via Transcutaneous Vagus Nerve Stimulation Background: The vagus nerve, a crucial component of the parasympathetic nervous system, serves as a vital communication link between the brain and body. Recent studies indicate that auricular stimulation of the vagus nerve can influence executive functions by increasing activity in brain regions like the prefrontal cortex. While prefrontal areas are associated with temporal processing, it remains unclear whether vagus nerve stimulation can also impact time perception. Hypothesis: The stimulation of the vagus nerve via its auricular branch may enhance performance in temporal processing by boosting activities in prefrontal brain areas related to temporal processing. Methods: Temporal processing abilities were assessed using an anisochrony detection task, where participants identified temporal irregularities in otherwise isochronous sequences while undergoing transcutaneous Vagus Nerve Stimulation (tVNS) or sham stimulation. Results: The results of this study, for the first time, revealed that participants could recognize smaller temporal shifts when the vagus nerve was stimulated, compared to the sham condition. Conclusion: The findings suggest that vagus nerve stimulation modulates temporal processing, supporting the notion that transcutaneous stimulation of the vagus nerve can influence cognitive functions related to temporal processing, possibly by enhancing prefrontal activities. (Comment on this)
12:36a	Functional architecture of intracellular oscillations in hippocampal dendrites Fast electrical signaling in dendrites is central to neural computations that support adaptive behaviors. Conventional techniques lack temporal and spatial resolution and the ability to track underlying membrane potential dynamics present across the complex three-dimensional dendritic arbor in vivo. Here, we perform fast two-photon imaging of dendritic and somatic membrane potential dynamics in single pyramidal cells in the CA1 region of the mouse hippocampus during awake behavior. We study the dynamics of subthreshold membrane potential and suprathreshold dendritic events throughout the dendritic arbor in vivo by combining voltage imaging with simultaneous local field potential recording, post hoc morphological reconstruction, and a spatial navigation task. We systematically quantify the modulation of local event rates by locomotion in distinct dendritic regions and report an advancing gradient of dendritic theta phase along the basal-tuft axis, then describe a predominant hyperpolarization of the dendritic arbor during sharp-wave ripples. Finally, we find spatial tuning of dendritic representations dynamically reorganizes following place field formation. Our data reveal how the organization of electrical signaling in dendrites maps onto the anatomy of the dendritic tree across behavior, oscillatory network, and functional cell states. (Comment on this)
12:36a	Reverse engineering placebo analgesia Placebo analgesia is a widely observed clinical phenomenon. Establishing a robust mouse model of placebo analgesia is needed for careful dissection of the underpinning circuit mechanisms. However, previous studies failed to observe consistent placebo effects in rodent models of chronic pain. We wondered whether strong placebo analgesia can be reverse engineered using general anesthesia-activated neurons in the central amygdala (CeAGA) that can potently suppress pain. Indeed, in both acute and chronic pain models, pairing a context with CeAGA-mediated pain relief produced robust context-dependent analgesia, exceeding that induced by morphine in the same paradigm. We reasoned that if the analgesic effect was dependent on reactivation of CeAGA neurons by conditioned contextual cues, the analgesia would still be an active treatment, rather than a placebo effect. CeAGA neurons indeed receive monosynaptic inputs from temporal lobe areas that could potentially relay contextual cues directly to CeAGA. However, in vivo imaging showed that CeAGA neurons were not re-activated in the conditioned context, despite mice displaying a strong analgesic phenotype, supporting the notion that the cue-induced pain relief is true placebo analgesia. Our results show that conditioning with activation of a central pain-suppressing circuit is sufficient to engineer placebo analgesia, and that purposefully linking a context with an active treatment could be a means to harness the power of placebo for pain relief. (Comment on this)
2:31a	Neurobiological slowdown in later life manifests in tempo of popular music Degradation of motor control across the adult lifespan due to neurobiological decay is well-established. Correspondences between the dynamics of motor behaviour and the timing of musical performance are also well-documented. In light of the former, the conspicuous absence of age as a mediating factor in investigation of the latter reveals a remarkable gap in our understanding of creative performance across the life course. To examine effects of ageing on musical timing, physical tempo of almost 2000 songs released by top-tier recording artists over their decades-long careers were annotated via a listening and tapping task. A series of regression analyses revealed i) an age-driven downward trend in performance tempo for all artists, ii) significant between-artist variation across time, and iii) within-artist variation that was independent of broader musical trends. Overall, tempo decreased by almost one and a half standard deviations from artists' early twenties to their late fifties, a rate of decline comparable to that observed in studies of spontaneous motor tempo. Results are consistent with the slowing-with-age hypothesis, and reveal that, not only is such tempo decline discernible in commercial recordings, the impact of age on tempo is overwhelming for artists most physically connected with their music. (Comment on this)
2:31a	Human color constancy in cast shadows Most natural scenes contain cast shadows to a varying extent. Illuminant conditions inside and outside the shadow typically differ largely both in intensity and in chromaticity. Nevertheless, our daily experiences suggest that colored materials appear to have the same color in shadows even though the reflected light from the material might be very different. Two experiments were conducted to reveal mechanisms that support human color constancy in cast shadows. In all experiments we built a real scene that consisted of colored hexagons illuminated by two independent liquid crystal projectors simulating sunlight and skylight, respectively. A part of the scene included a cast shadow under which observers were instructed to change the luminance and the chromaticity of a test field so that it appeared as a full-white paper under the shadow. The color of the skylight was manipulated, testing if our visual system uses a prior that the skylight is typically bluish or yellowish to achieve color constancy. We also created a condition where a cast shadow is not recognized as a shadow. Results showed that color constancy generally holds well in shadows and changing skylight color had little effect. Recognizing a cast shadow as a shadow also had no effect. Overall, these results are consistent with our daily experiences that we stably judge surface color even in shadows, providing a key step to reveal mechanisms of color perception in real-world scenes where lighting conditions spatially vary. (Comment on this)
11:47a	Most axonal mitochondria in cortical pyramidal neuronslack mitochondrial DNA and consume ATP In neurons of the mammalian central nervous system (CNS), axonal mitochondria are thought to be indispensable for supplying ATP during energy-consuming processes such as neurotransmitter release. Here, we demonstrate using multiple, independent, in vitro and in vivo approaches that the majority (~80-90%) of axonal mitochondria in cortical pyramidal neurons (CPNs), lack mitochondrial DNA (mtDNA). Using dynamic, optical imaging analysis of genetically encoded sensors for mitochondrial matrix ATP and pH, we demonstrate that in axons of CPNs, but not in their dendrites, mitochondrial complex V (ATP synthase) functions in a reverse way, consuming ATP and protruding H+ out of the matrix to maintain mitochondrial membrane potential. Our results demonstrate that in mammalian CPNs, axonal mitochondria do not play a major role in ATP supply, despite playing other functions critical to regulating neurotransmission such as Ca2+ buffering. (Comment on this)
11:47a	Short-term memory capacity predicts willingness to expend cognitive effort for reward We must often decide whether the effort required for a task is worth the reward. Past rodent work suggests that willingness to deploy cognitive effort can be driven by individual differences in perceived reward value, depression, or chronic stress. However, many factors driving cognitive effort deployment - such as short-term memory ability - cannot easily be captured in rodents. Furthermore, we do not fully understand how individual differences in short-term memory ability, depression, chronic stress, and reward sensitivity impact cognitive effort deployment for reward. Here, we examined whether these factors predict cognitive effort deployment for higher reward in an online visual short-term memory task. Undergraduate participants were grouped into high and low effort groups (nHighEffort = 348, nLowEffort = 81; nFemale = 332, nMale = 92, MAge = 20.37, RangeAge = 16-42) based on decisions in this task. After completing a monetary incentive task to measure reward sensitivity, participants completed short-term memory task trials where they could choose to encode either fewer (low effort/reward) or more (high effort/reward) squares before reporting whether or not the colour of a target square matched the square previously in that location. We found that only greater short-term memory ability predicted whether participants chose a much higher proportion of high vs. low effort trials. Drift diffusion modelling showed that high effort group participants were more biased than low effort group participants towards selecting high effort trials. Our findings highlight the role of individual differences in cognitive effort ability in explaining cognitive effort deployment choices. (Comment on this)
11:47a	The ChAHP chromatin remodelling complex regulates neurodevelopmental disorder risk genes to scale the production of neocortical layers Although chromatin remodellers are among the most important risk genes associated with neurodevelopmental disorders (NDDs), the roles of these complexes during brain development are in many cases unclear. Here, we focused on the recently discovered ChAHP chromatin remodelling complex. The zinc finger and homeodomain transcription factor ADNP is a core subunit of this complex, and de novo ADNP mutations lead to intellectual disability and autism spectrum disorder. However, germline Adnp knockout mice were previously shown to exhibit early embryonic lethality, obscuring subsequent roles for the ChAHP complex in neurogenesis. Here, we employed single cell transcriptomics, cut&run-seq, and histological approaches to characterize mice conditionally ablated for the ChAHP subunits Adnp and Chd4. We show that during neocortical development, Adnp and Chd4 orchestrate the production of late-born, upper-layer neurons through a two-step process. First, Adnp is required to sustain progenitor proliferation specifically during the developmental window for upper-layer cortical neurogenesis. Accordingly, we found that Adnp recruits Chd4 to genes associated with progenitor proliferation. Second, in postmitotic differentiated neurons, we define a network of risk genes linked to NDDs that are regulated by Adnp and Chd4. Taken together, these data demonstrate that ChAHP is critical for driving the expansion upper-layer cortical neurons, and for regulating neuronal gene expression programs, suggesting that these processes may potentially contribute to NDD etiology. (Comment on this)
11:47a	A nociceptive amygdala-striatal pathway for chronic pain aversion The basolateral amygdala (BLA) is essential for assigning positive or negative valence to sensory stimuli. Noxious stimuli that cause pain are encoded by an ensemble of nociceptive BLA projection neurons (BLAnoci ensemble). However, the role of the BLAnoci ensemble in mediating behavior changes and the molecular signatures and downstream targets distinguishing this ensemble remain poorly understood. Here, we show that the same BLAnoci ensemble neurons are required for both acute and chronic neuropathic pain behavior. Using single nucleus RNA-sequencing, we characterized the effect of acute and chronic pain on the BLA and identified enrichment for genes with known functions in axonal and synaptic organization and pain perception. We thus examined the brain-wide targets of the BLAnoci ensemble and uncovered a previously undescribed nociceptive hotspot of the nucleus accumbens shell (NAcSh) that mirrors the stability and specificity of the BLAnoci ensemble and is recruited in chronic pain. Notably, BLAnoci ensemble axons transmit acute and neuropathic nociceptive information to the NAcSh, highlighting this nociceptive amygdala-striatal circuit as a unique pathway for affective-motivational responses across pain states. (Comment on this)
11:33p	Assessing the effects of an 8-week mindfulness training program on neural oscillations and self-reports during meditation practice Previous literature suggests that mindfulness meditation can have positive effects on mental health, however, its mechanisms of action are still unclear. In this pre-registered study, we investigate the effects of mindfulness training on lapses of attention (and their associated neural correlates) during meditation practice. For this purpose, we recorded Electroencephalogram (EEG) during meditation practice before and after 8 weeks of mindfulness training (or waitlist) in 41 participants (21 treatment and 20 controls). In order to detect lapses of attention and characterize their EEG correlates, we interrupted participants during meditation to report their level of focus and drowsiness. First, we show that self-reported lapses of attention during meditation practice were associated to an increased occurrence of theta oscillations (3-6 Hz), which were slower in frequency and more spatially widespread than theta oscillations occurring during focused attention states. Then, we show that mindfulness training did not reduce the occurrence of lapses of attention nor their associated EEG correlate (i.e. theta oscillations) during meditation. Instead, we find that mindfulness training was associated with a significant slowing of alpha oscillations in frontal electrodes during meditation. Crucially, frontal alpha slowing during meditation practice has been reported in highly experienced meditators and is thought to reflect relative decreases in arousal levels. Together, our findings provide insights into the EEG correlates of mindfulness meditation, which could have important implications for the identification of its mechanisms of action and/or the development of neuromodulation protocols aimed at facilitating meditation practice. (Comment on this)
11:34p	Estimating orientation in Natural scenes: A Spiking Neural Network Model of the Insect Central Complex The central complex of insects contains cells, organised as a ring attractor, that encode head direction. The bump of activity in the ring can be updated by idiothetic cues and external sensory information. Plasticity at the synapses between these cells and the ring neurons, that are responsible for bringing sensory information into the central complex, has been proposed to form a mapping between visual cues and the heading estimate which allows for more accurate tracking of the current heading, than if only idiothetic information were used. In Drosophila, ring neurons have well characterised non-linear receptive fields. In this work we produce synthetic versions of these visual receptive fields using a combination of excitatory inputs and mutual inhibition between ring neurons. We use these receptive fields to bring visual information into a spiking neural network model of the insect central complex based on the recently published Drosophila connectome. Previous modelling work has focused on how this circuit functions as a ring attractor using the same type of simple visual cues commonly used experimentally. While we initially test the model on these simple stimuli, we then go on to apply the model to complex natural scenes containing multiple conflicting cues. We show that this simple visual filtering provided by the ring neurons is sufficient to form a mapping between heading and visual features and maintain the heading estimate in the absence of angular velocity input. The network is successful at tracking heading even when presented with videos of natural scenes containing conflicting information from environmental changes and translation of the camera. (Comment on this)
11:34p	Mitochondrial bioenergetics stimulates autophagy for pathological tau clearance in tauopathy neurons Hyperphosphorylation and aggregation of microtubule-associated tau is a pathogenic hallmark of tauopathies and a defining feature of Alzheimer's disease (AD). Pathological tau is targeted by autophagy for clearance, but autophagy dysfunction is indicated in tauopathy. While mitochondrial bioenergetic failure has been shown to precede the development of tau pathology, it is unclear whether energy metabolism deficiency is involved in tauopathy-related autophagy defects. Here, we reveal that stimulation of anaplerotic metabolism restores defective oxidative phosphorylation (OXPHOS) in tauopathy which, strikingly, leads to enhanced autophagy and pronounced tau clearance. OXPHOS-induced autophagy is attributed to increased ATP-dependent phosphatidylethanolamine biosynthesis in mitochondria. Excitingly, early bioenergetic stimulation boosts autophagy activity and reduces tau pathology, thereby counteracting memory impairment in tauopathy mice. Taken together, our study sheds light on a pivotal role of bioenergetic dysfunction in tauopathy-linked autophagy defects and suggests a new therapeutic strategy to prevent toxic tau buildup in AD and other tauopathies. (Comment on this)
11:34p	Using high-resolution functional MRI to differentiate impacts of strabismic and anisometropic amblyopia on evoked ocular dominance activity in humans We employed high-resolution functional MRI (fMRI) to distinguish the impacts of anisometropia and strabismus (the two most frequent causes of amblyopia) on the evoked ocular dominance (OD) response. Sixteen amblyopic participants (8 females), comprising 8 individuals with strabismus, 7 with anisometropia, 1 with deprivational amblyopia, along with 8 individuals with normal visual acuity (1 female), participated in this study for whom, we measured the difference between the response to stimulation of the two eyes, across early visual areas (V1-V4). In controls, as expected from the organization of OD columns, the evoked OD response formed a striped pattern that was mostly confined to V1. Compared to controls, the OD response in amblyopic participants formed larger fused patches that extended into downstream visual areas. Moreover, both anisometropic and strabismic participants showed stronger OD responses in V1, as well as in downstream visual areas V2-V4. Although this increase was most pronounced in V1, the correlation between the OD response level and the interocular visual acuity difference (measured behaviorally) was stronger in higher-level visual areas (V2-V4). Beyond these common effects, and despite similar densities of amblyopia between the anisometropic and strabismic participants, we found a greater increase in the size of V1 portion that responded preferentially to fellow eye stimulation in anisometropic compared to strabismic individuals. We also found a greater difference between the amplitudes of the response to binocular stimulation, in those regions that responded preferentially to the fellow vs. amblyopic eye, in anisometropic compared to strabismic subjects. In contrast, strabismic subjects demonstrated increased correlation between the OD responses evoked within V1 superficial and deep cortical depths, whereas anisometropic subjects did not. These results provide some of the first direct functional evidence for distinct impacts of strabismus and anisometropia on the mesoscale functional organization of the human visual system, thus extending what was inferred previously about amblyopia from animal models. (Comment on this)
11:34p	Locus coeruleus injury modulates ventral midbrain neuroinflammation during DSS-induced colitis Parkinson's disease (PD) is characterized by a decades-long prodrome, consisting of a collection of non-motor symptoms that emerges prior to the motor manifestation of the disease. Of these non-motor symptoms, gastrointestinal dysfunction and deficits attributed to central norepinephrine (NE) loss, including mood changes and sleep disturbances, are frequent in the PD population and emerge early in the disease. Evidence is mounting that injury and inflammation in the gut and locus coeruleus (LC), respectively, underlie these symptoms, and the injury of these systems is central to the progression of PD. In this study, we generate a novel two-hit mouse model that captures both features, using dextran sulfate sodium (DSS) to induce gut inflammation and N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP-4) to lesion the LC. We first confirmed the specificity of DSP-4 for central NE using neurochemical methods and fluorescence light-sheet microscopy of cleared tissue, and established that DSS-induced outcomes in the periphery, including weight loss, gross indices of gut injury and systemic inflammation, the loss of tight junction proteins in the colonic epithelium, and markers of colonic inflammation, were unaffected with DSP-4 pre-administration. We then measured alterations in neuroimmune gene expression in the ventral midbrain in response to DSS treatment alone as well as the extent to which prior LC injury modified this response. In this two-hit model we observed that DSS-induced colitis activates the expression of key cytokines and chemokines in the ventral midbrain only in the presence of LC injury and the typical DSS-associated neuroimmune is blunted by pre-LC lesioning with DSP-4. In all, this study supports the growing appreciation for the LC as neuroprotective against inflammation-induced brain injury and draws attention to the potential for NEergic interventions to exert disease-modifying effects under conditions where peripheral inflammation may compromise ventral midbrain dopaminergic neurons and increase the risk for development of PD. (Comment on this)
11:34p	Sapap3 knockout mice show threat bias under conflict during platform mediated avoidance task: implications for obsessive compulsive disorder Obsessive compulsive disorder (OCD) typically involves cycling between symptoms of intrusive aversive thoughts (obsessions) and repetitive rituals aimed at avoiding these aversive outcomes (compulsions), which interferes with patients' engagement with other important aspects of their lives. This cycling relationship between obsessions and compulsions highlights a potential role of impaired threat processing and avoidance behavior in OCD symptoms. The most effective behavioral therapy for OCD, exposure with response prevention (ERP), aims to break this cycle. However, it can be difficult for patients to access and engage with, suggesting a need for improved understanding of the neural mechanisms of threat processing and avoidance behavior in OCD to guide development of new and more effective treatments. Platform mediated avoidance (PMA) has proven to be a useful translational paradigm for use in rodents to examine avoidance neurobiology and models relevant to OCD, such as ERP and overtraining-induced persistent avoidance. However, to date this protocol has only been used in rats, and studies in transgenic mouse models relevant to OCD may shed further light on neural mechanisms relevant to disturbances in avoidance and threat processing in the disorder. To address this gap, we tested Sapap3 knockout (KO) mice, a leading preclinical model in OCD research, in the PMA task. Using this paradigm, we examined avoidance acquisition, expression, and extinction, as well as reward seeking under motivational conflict in two separate cohorts conditioned using higher (0.4 mA) or lower (0.24 mA) intensity shock. Surprisingly, the most striking difference observed in Sapap3-KOs vs control mice was heightened suppression of lever pressing for rewards during a tone signaling impending threat, suggesting a shift in action selection under motivational conflict (genotype effect avoidance conditioning: 0.24 mA cohort p=0.011, 0.4 mA cohort p=0.07; avoidance extinction: 0.24 mA p=0.057, 0.4 mA p=0.042). Avoidance responding was also acquired more slowly in Sapap3-KOs trained with a low intensity shock (time x genotype interaction p=0.025) and was extinguished more robustly following ERP (genotype effect p=0.043). In contrast, avoidance was similar between Sapap3 KOs and WT littermate controls trained using higher intensity shock (0.4 mA cohort time effect p<0.0001). Expression of the immediate early gene c-Fos associated with reinstatement of avoidance after ERP showed preliminary evidence for decreased activity of medial orbitofrontal cortex (mOFC) in KOs which may contribute to observed differences in PMA performance (KO vs WT mOFC c-Fos t-test p=0.0456). Together these findings suggest that mOFC dysfunction may contribute to increases in the influence of threats vs rewards over action selection in an animal model with relevance to OCD, and that the Sapap3-KO model presents valuable opportunities for deeper mechanistic investigation of avoidance and threat processing relevant to the human disorder. (Comment on this)
11:34p	Identifying Reproducibly Important EEG Markers of Schizophrenia with an Explainable Multi-Model Deep Learning Approach The diagnosis of schizophrenia (SZ) can be challenging due to its diverse symptom presentation. As such, many studies have sought to identify diagnostic biomarkers of SZ using explainable machine learning methods. However, the generalizability of identified biomarkers in many machine learning-based studies is highly questionable given that most studies only analyze explanations from a small number of models. In this study, we present (1) a novel feature interaction-based explainability approach and (2) several new approaches for summarizing multi-model explanations. We implement our approach within the context of electroencephalogram (EEG) spectral power data. We further analyze both training and test set explanations with the goal of extracting generalizable insights from the models. Importantly, our analyses identify effects of SZ upon the alpha, beta, and omega frequency bands, the left hemisphere of the brain, and interhemispheric interactions across a majority of folds. We hope that our analysis will provide helpful insights into SZ and inspire the development of robust approaches for identifying neuropsychiatric disorder biomarkers from explainable machine learning models. (Comment on this)

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